Mistake No. 4: Not eating enough -- or often enough.
While overeating and undereating may seem like contradictory nutrition mistakes, they are related.
"If you don't eat at regular intervals throughout the day, you risk disrupting your blood sugar and insulin levels, which in the end can promote fat storage and lower your metabolism -- both of which lead to weight gain," Brandeis says.
The solution: Eat something every four hours and never let yourself "starve" from one meal to the next, Brandeis says.
Mistake No. 5: Taking too many supplements.
"People tend to forget that a vitamin pill is a supplement -- it's meant to complement your diet, not act as a stand-in for the foods you don't eat," says Heller. What's more, she says, taking too many vitamins can end up sabotaging your good health.
"Every vitamin and mineral and phytochemical in our body works in concert with one another, and it's easy to knock that balance off if you are taking concentrated doses of single nutrients, or even groups of nutrients," says Heller.
Bradeis cautions that any diet plan that claims you must take a high-potency supplement to meet your nutritional needs should send up a red flag.
"It means that eating plan is not healthy," says Brandeis, "and it also means you are going to miss out on the synergistic health effects that can only come from whole foods -- including not only helping you to feel fuller longer, but also preventing cellular breakdowns important to preventing disease."
The solution: Both experts recommend taking no more than one all-purpose multivitamin daily. Don't supplement your diet with individual nutrients without the guidance of your doctor, nutritionist, or other health expert. Keep in mind that the sales clerk in the health food store is usually not a health expert.
Mistake No. 6: Excluding exercise.
While most folks believe nutrition is all about food, Brandeis says it's also about how your body uses food -- and that's where regular exercise comes in.
"Without adequate exercise, you cannot maintain a high enough metabolic rate to burn your food efficiently," says Brandeis. "A pill can't do that for you; foods alone can't do that for you. Exercise is the only way to achieve it."
The solution: Make exercise a regular part of your life. And don't get hung up if you can't do it at the same time every day. If you miss your routine in the morning, don't wait until the next day and try to do twice as much. Instead, try to fit in some exercise -- even if it's just a little bit -- every day, says Taub-Dix.